Enhancing Bandwidth and Back-Off Range of Doherty Power Amplifier With Modified Load Modulation Network

This article presents a novel methodology for designing broadband Doherty power amplifier (DPA) with extended output back-off (OBO) range. A modified load modulation network (LMN) is proposed to enhance the OBO range and bandwidth of DPA simultaneously. Analysis conducted explore relationship between LMN parameters performance under various levels. Generalized design formulas are then introduced offer solution arbitrary current ratios An asymmetric demonstrated implemented gallium nitride (GaN) transistors using approach. The fabricated operates from 1.4 2.5 GHz 9-dB measured drain efficiency reaches 61%-75.5% at saturation 44.6%-54.6% within operating bandwidth. When driven by 60-MHz modulated signal peak-to-average ratio (PAPR), attains 47.4%-53.5% average better than -45.5-dBc adjacent channel leakage (ACLR) after digital predistortion.